Guides to house number and streetname changes
from the Chicago History Museum
Guide to 1909 house number changes outside downtown (170MB PDF)
Guide to 1911 house number changes downtown (47MB PDF)
Guide to streetname changes (small PDF)

Digital Public Library of America catalog
of maps from various online collections
excellent, easy-to-use search tool for multiple resources

The online Encyclopedia of Chicago
includes maps from the published book and other maps
from the Chicago History Museum

University of Chicago map library
online digital collection

TopoView historic USGS topo viewer
View and download historic USGS topo maps

Historic USGS topo viewer
Uses ESRI online viewer: double-click rather than scroll to zoom in

David Rumsey map collection
enormous online collection of historic maps

Library of Congress Images of America
primarily 19th century birds-eye views

Newberry Library Chicago and the Midwest
online collection maps

Harvard University map library
online digital collection

Northwestern University map library
online digital collection includes fire insurance atlases

New York Public Library map collection
alternative access via MapWarper to maps that won’t load

University of Alabama
collection of national atlas maps of Chicago

NOAA Coast Survey historic charts
collection of coastal charts, including the Lake Michigan coastline

University of Wisconsin–Milwaukee
more than 100 historic maps of Chicago

Historic Illinois highway maps
Link to downloadable PDFs

Indiana historic maps at IUPUI
historic maps of the Calumet Region

Texas A&M University
1902 Geologic Atlas folio of Chicago area
topo maps on pages 15-18

Sanborns Fire Insurance Maps online
at the Library of Congress

Historic Chicago transit maps
online at Illinois Railway Museum

Historic Chicago transit maps
at Chicago-L.org

Smoke Abatement maps of Chicago railroads & industry
download full 1915 report (1177 pages) in PDF format from archive.org
download 151 map pages only in PDF format

Chicago Land Use Survey
Vol. I: Residential Chicago
Vol. II: Land Use in Chicago
full 1942 reports in PDF format from archive.org

Aerial photos of Cook County 1938
choose location from an online map and download

Historic aerial photos
from HistoricAerials.com

Original surveyors maps and notes for Cook County
prior to land sales and extensive European settlement